A photopolymerizable composition comprising (A) a monomer having at least two terminal unsaturated groups which are photopolymerizable upon irradiation with actinic rays and (B) as a photopolymerization accelerator for the unsaturated monomer, a compound represented by the formula:...http://www.google.fr/patents/US3870524?utm_source=gb-gplus-shareBrevet US3870524 - Photopolymerizable composition

A photopolymerizable composition comprising (A) a monomer having at least two terminal unsaturated groups which are photopolymerizable upon irradiation with actinic rays and (B) as a photopolymerization accelerator for the unsaturated monomer, a compound represented by the formula:

where Z represents a non-metallic atomic group necessary to form a heterocyclic nucleus containing a nitrogen atom; R represents an alkyl group or a substituted alkyl group; and R represents an alkyl group or an aryl group.

11 Claims, No Drawings 1 PHOTOPOLYMERIZABLE COMPOSITION BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photopolymerizable composition comprising an unsaturated monomer and a photopolymerization accelerator for the unsaturated monomer, and more particularly, to a photopolymerizable composition which can provide photohardenable images useful for making printing plates, photo resists and the like.

2. Description of the Prior Art 7 It is well known to reproduce images by photographic methods using a light-sensitive composition comprising an addition-polymerizable unsaturated monomer, a photopolymerization accelerator therefor and, if desired, a soluble polymer having an appropriate filmforming capability, a thermal-polymerization inhibitor,

etc. That is, as described in US Pat. No. 2,929,022 and 2,902,365, since the above-described lightsensitive composition becomes insoluble as the result of photopolymerization when it is irradiated with actinic rays, the desired photopolymerized images can be formed by forming an appropriate film of the lightsensitive composition, irradiating the film with actinic rays through a desired negative original and then removing the unexposed areas with an appropriate solvent. Needless to say, this type of light-sensitive composition is extremely useful as a light-sensitive material for making printing plates, photo resists, etc.

It has been proposed heretofore that a photopolymerization accelerator be added to the light-sensitive composition to enhance the sensitivity since the unsaturated monomer along is insufficient in sensitivity. Specific examples of such photopolymerization accelerators are benzylbenzoin, pivaloin, benzoin methyl ether, benzophenone, etc., the substituted compounds thereof, and polynuclear quinones such as anthraquinone, naphthoquinone or phenanthraquinone, and the substituted compounds thereof. However, these compounds do not provide sufficient sensitivity for practical purposes due to the fact that the wavelength of actinic rays necessary is in a comparatively short wavelength region and thus a long period of time is required to form images with light exposure.

As the result of various invenstigations, the inventors have found a series of compounds having a high accelerating effect for photopolymerization.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a photopolymerizable composition having high sensitivity. This and other objects are achieved by the photopolymerizable composition of this invention which comprises A. a monomer having at least two teminal unsaturated groups and capable of being photopolymerized upon irradiation with actinic rays and B. as a photopolymerization accelerator for the unsaturated monomer, a compound represented by the formula:

an ethyl group, a propyl group, etc., or a substitutedalkyl group such as a hydroxyalkyl group(e.g., a 2- hydroxyethyl group), an alkoxyalkyl group (e.g., a 2- methoxyethyl group), a carboxyalkyl group, (e.g., a carboxymethyl group, a 2-carboxyethyl group, a 3-car boxypropyl group) a sulfoalky group (e.g., a 2- sulfoethyl group, a 3-sulfopropyl group), a carboxyalkoxyalkyl group (e.g., a 2-carbomethoxyethyl group), an aralkyl group (e.g. a benzyl group, a phenethyl group), a sulfoaralkyl group (e.g., a p-sulfophenethyl group), a carboxy-aralkyl group (e.g., a p-carboxyphenethyl group), a vinylmethyl group, etc.; R represents and alkyl group, such as a methyl group, and ethyl group, etc., or an aryl group, (e.g., a phenyl group, a naphtyl group) a hydroxyaryl group(e.g., a p-hydroxyphenyl group), an alkoxyaryl group(e.g., a p-methoxyphenyl group), a haloaryl group(e.g., a p-chlorophenyl group), a thienyl group, etc.; Z represents a non-metallic atomic group necessary for forming a nitrogencontaining heterocyclic nuclus which is generally used in cyanine dyes, e.g., a benzothiazole such as benzothiazole, 5-chlorobenzothiazole, 6-chlorobenzothiazole,

hydroxy-benzothiazole, 5,6-dimethylbenzothiazole, 5,6-dimethoxybenzothiazole, etc., a naphthothiazole such as a-naphthothiazole, B-naphthothiazole, a benzoselenazole such as benzoselenazole, 5- chlorobenzoselenazole, 6-methylbenzoselenazole, 6- methoxybenzoselenazole, etc., a naphthoselenazole such as LI-I'IKPIIIIIOSBIEIIHZOIC, B-naphthoselenazole, etc., a benzoxazole such as benzoxazole, 5- methylbenzoxazole, S-phenylbenzoxazole, 6- methyoxybenzoxazole, etc., a naphthoxazole such as a-naphthoxazole, B-naphthoxazole, etc.

DETAILED DESCRIPTION OF THE INVENTION The unsaturated monomer used in this invention possesses at least two terminal unsaturated groups and is photopolymerizable upon irradiation with actinic rays. Examples of the monomer are described in US. Pat. Nos. 2,760,863; 2,791,504; 3,060,023; etc,. which include acrylates or methacrylates of polyols. Suitable polyols are those compounds having at least two aliphatic hydroxy groups, preferably having 2 to 5 aliphatic hydroxy groups and having from 2 to 12 carbon atoms. There are, for example, diols such as ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, 1,4-butane diol, 1,5-pentane diol, polycyclohexane oxide, polystyrene oxide, cyclohexane diol, xylylene diol, di-(B-hydroxyethoxy)benzene; polyols such as glycerine, diglycerine,'trimethylol propane, triethylolpropane, pentaerythritol, and the like. Specific examples are e.g., diethyleneglycol-diacrylate(dimethacrylate), triethyleneglycoldiacrylate-(dimethacrylate), pentaerythritholtriacrylate(trimethacrylate), trimethylolpropane-- isocyanates, or the like. Suitable diols for the diol monoacrylates are those diols as described in detail above. Suitable unsaturated monomers which can be used in this invention are described in detail in US. Pat. Nos. 2,760,863; 2,791,504; and 3,060,023.

Typical examples of the thiazoline derivatives which are a type of photopolymerization accelerator used in the present invention are set forth below. The number in pararences as set forth below references these compounds to Example l given hereinafter.

5 N =CH-C=O 4H,

Z =CH -c=o 2.

/ I S =CH-C i I 2 s l I N =CH-C=O 2 5 on s 5 QN =CHJI=O .1

(VII) (VIII) I c H =CH-C=O N 4 ,3 1 =cH- =0 v N HZCHZCOOH (([JH2)5SO5H (XIII) The thiazolone derivatives used in the present invention also include those which are already known as sensitizers for azide resins or cinnamic acid ester type light-sensitive resins as described in US. Pat. No. 2,948,610 and German OLS No. 2,012,390. The above fact, however, does not detract from the unexpectedness of this invention.

That is, there is a fundamental difference in mechanism between the sensitizers in those known techniques and the photopolymerization accelerator in this invention since the sensitizers for the azide resins or the cinnamic acid ester type light-sensitive resins simply act to cause an energy transfer while the compound of this invention acts to cause polymerization (as a photopolymerization initiator) by forming seeds for initiating the polymerization, and further a feature of this invention lies in the combination of the aforesaid photopolymerization accelerator and a monomer which has atleast two terminal unsaturated groups and is photopolymerizable due to irradiation with actinic rays.

In general, the concentration of the photopolymerization accelerator to be used is low and a unduly high concentration causes undesired results such ash shielding from effective rays. The photopolymerization accelerator of the present inventioncan effectively be used in the range of 0.01 to 30 wt percent to the amount of the unsaturated monomer. More preferably, excellent results can be obtained when the photopolymerization accelerator is used in an amount of l to wt percent to the amount of the unsaturated monomer.

The aromatic sulfonyl halide can be used in an amount so that the total amount of the photopolymerization accelerator and the aromatic sulfonyl halide range from about 0.01 to 30 wt percent preferably 1 to 10 wt percent to the unsaturated monomer.

As described heretobefore, the composition of this invention can contain a soluble polymer. Specific examples of suitable soluble polymers which can be used include addition polymers having carboxy groups on the side chain thereof, e.g., acrylic acid/methyl methacrylate copolymer, styrene/acrylic acid copolymer, etc., cellulose derivatives similarly having carboxy groups on the side chains thereof; polyvinyl alcohol derivatives; soluble polyamides; polyurethanes; and the like. These soluble polymers can be incorporated in the Table 1 Sample No.

composition in an optional amount, but an amount exceeding wt percent undesirable from the standpoint of, e.g., the fastness of images formed. In accordance with the present invention, a small amount of a thermal polymerization inhibitor can be incorporated in the composition in order to prevent the occurrence of undesired thermal polymerization of the unsaturated monomer in the preparation of or during storage of light-sensitive composition. In most cases, improved storability can be expected due to the addition of thermal polymerization inhibitors. Suitable examples of thermal polymerization inhibitors include hydroquinone, p-methoxyphenol, di-tertbutyl-p-cresol, pyrogallol, tert-butylcatechol, methlene blue, etc. A generally used amount ranges from about 0.01 to 5 wt percent to the amount of the unsaturated monomer.

If desired, dyes or pigments can be added for the purpose of coloration.

EXAMPLE 1 In 153 parts by weight of methyl cellosolve were dissolved 4 parts by weight of hydrogen acetate phthalic acid cellulose ester, 12 parts by weight of di(2-methacryloxyethyl)'2,4- tolylene diurethane, 0.2 part by weight of methylene blue and 0.8 part by weight of a photopolymerization accelerator shown in Table 1 below to produce a coatingsolution. After immersing an aluminum plate having a thickness of 0.3 'mm in a sodium triphosphate solution of 70C for 3 mins., the aluminum plate was thoroughly washed with water and dried. The coating solution and dried. The coating solution described above was coated onto the thus obtained aluminum plate using a revolving coating method. The aluminum plate was dried at C for 2 mins.to obtain a light-sensitive plate. The coated amount was about 2.0 g/m on a dry basis.

The light-sensitive plate was exposed through an LTF step wedge having a step density difference of 0.15 to a single phase carbon arc lamp of 30 A from a distance of 30 cm to print the step wedge thereon. Thereafter, the light-sensitive element was developed with a 3 percent sodium triphosphate solution. The results obtained are also shown in Table 1 below, where the step number which is rendered insolubleby photopolymerization conrresponds to the sensitivity. These results clearly demonstrate that the use of the accelerators (l1 XIII) in accordance with the present invention give excellent sensitivity as compared to the case of adding no accelerator (1I), or the case of using the prior art benzophenone (Accelerator I).

(LH CH OCH (XIII) Se 1 lb @li =CH- =0 10 EXAMPLE 2 A light-sensitive plate was produced in a similar manner to Example 1 in accordance with the formulation shown below.

parts by weight Methyl Methacrylate/Methacrylic 30 Acid Copolymer Trimethylolpropane Triacrylate l5 Photopolymerization Accelerator* 0.75 Methyl Ethyl Ketone 60 as shown in Table 2 below The thus produced light-sensitive plate was expsoed through an. LTF step wedge having a step density difference of 0.15 with a chemical lamp exposure apparatus of 100 V and W for 3 mins. Then, the light-sensitive plate was developed with a developer consisting of 1.2 20 g of sodium hydroxide, 300 cc of isopropyl alcohol and 900 cc of water to remove the unexposed areas. The number of the step photohardened-after development is shonw in Table 2 below. In particular, it can clearly be seen from the results in Table 2 that 2- benzoylmethylene-3-ethy lnaphthothiazoline has an extremely excellent photopolymerization accelerating effect.

Table 2 j Sample No. Photopolymerization Number of Developed Accelerator Step 2-1 Compound lll of Table l 7 (2-Benzoylmethylene-3- ethylnaphthothiazoline) 2-2 Michler's Ketone 2.5 2-3 Phenanthraquinone 4.5 2-4 tert-Butylanthraquinone 3.5 2-5 0 Benzoin Methyl Ether A similar light-sensitive plate was exposed through a 4 dot nagative instead of the step wedge and developed to produce a lithographic printing plate. Upon use of the printing plate, printing was conducted with an offset printing machine in a conventional manner. In using the printing plate obtained from Sample 2-1, more than 50,000 satisfactory copies were obtained. On the contrary, in using the printing plates obtained from Sample 2-2 and Sample 2-4, respectively, the printed images became unclear in printing between 10,000 20,000 copies and the printing of more than 20,000 copies was impossible. From Sample 2-5 no printing plate which could be used for printing could be obtained.

From the above results, it can be seen that in using Compound III of this invention, not only can high sensi- 5 5 tivity be obtained but also the printability is superior.

EXAMPLE 3 A light-sensitive liquid having the following composi' tion was prepared.

parts by weight Polymethyl Methacrylate 2O (Toray Industries, Inc.) Trimeth ololpropane Trimethacrylate 5 Dioctyl hthalate 2 Photopolymerization Accelerator 0.4 (Compound lll of Table l) Methylene Blue 0.6 Methyl Eth l Ketone Dimethylsu foxide 30 .above was laminated onto the surface of the coppercoated laminate plate treated as described above, which was then heated to 140C and then pressed and adhered together. After stripping of the polyethylene terephthalate film, the remaining plate was exposed for 5 mins. with a high pressure mercury lamp of 400 W at a distance of 30 cm through a negative original for a print wire and then developed with trichloroethylene, whereby the unexposed areas were dissolved and removed. As the result, blue resist images which correspond to the negative original were formed on the copper plate. The copper plate was then etched with a ferric chloride solution (40 Baume). After washing with water, the light-sensitive layer was removed with methylene chloride to give the desired clear print wire plate.

' EXAMPLE v4 A light-sensitive liquid was prepared except that Compound V was employed as a photopolymerization accelerator instead of Compound III in the composition of Example 3. The thus obtained light-sensitive liquid was spray coated onto a zinc plate for a relief printing and dried. The zinc plate was exposed using a carbon arc lamp in intimate contact with a dot negative and then developed using trichloroethylene. The plate was etched with nitric acid togive the desired printing plate for a relief printing.

EXAMPLE 5 (A) g of hydroxypropylmethylacetylcellulose hexahydrophthalate (l-lPMA CHP) [degreeof substitution: hydroxypropyl group: methyl group: acetyl group =0.l8 1.35 1.43; degree of hexahydrophthalyl group O substitution; 0.85; viscosity, 93.2 cps (acetone/methanol 7/3 by volume mixed solvent, 20C], 20 g of glycidylmethacrylate 6.4 g of triethylamine, 0.024 g of hydroquinone and 200 g of acetone as a solvent were mixed together, and were reacted for a week at 50C. After the reaction the mixture was diluted with methanol and the polymer was precipitated by pouring the solution into an excessive amount of water. The polymer was dried with hot air at 40C after filtration to obtain glycidyl methacrylate denaturated acidic cellulose derivative (GMA-HPMACHP). Using a weak-alkali soluble linear organic high molecular weight polymer having pendant carboxy groups and a methacrylate groups as a film forming agent, the following light sensitive solution was prepared.

[1,2-al-thiazole Methylcellosolveacetate Table 3 Sensitivity of 2-Naphthalenesulfonylchloride and 3- Methyl-2-benzoylmethylenenaphtho[1,2-a1- thiazole as a Mixed Photopolymerization Initiator Z'Naphthalene- 3-M ethyl-2-benzoyl- Development sulfonylchloride methylenenaphtho- Step Number [l,2'a]thiazole Table 3 Continued 2-Naphthalene- 3-Methyl-2-benzoyl- Development sulfonylchloride methylenenaphtho' Step Number [LZ-althiazole As is apparent from the above results, the sensitivity is very low when only Z-naphthalenesulfonylchloride or B-methyl-2-benzoylmethylenenaphtho[ l ,2-a]thiazole was used, but the sensitivity is increased by combining these accelerators.

EXAMPLE 6 The sensitivity (development step number) was obtained under the same conditions except that the thiazole derivatives of Table 4 were used instead of the 3- methyl-Z-benzoylmethylenenaphtho[ l ,2-a]thiazole as a photopolymerization accelerator of Example 5. 2 Weight percent (0.02 g) of Z-naphthalenesulfonylchloride was used in combination therewith.

Table Aromatic Sulfonyl Chloride Sensitivity 2 M71 (0.02 g) (development step No.) Z-Naphthalenesulfonylchloride l4 (Example 5) p-Toluenesul onylchloride l2 Toluene-3,4-disulfonylchloride l4 EXAMPLE 8 After 65 g of methacrylic acid/methylmethacrylate copolymer (:85 weight ratio), 0.27 g of trimethylolpropanetriacrylate, 0.08 g of dioctylphthalate, 0.02 g of 3-methyl-2-benzoylmethylenenaphtho[ l ,2-a]thiazole, 0.02 g of 2-naphthalenesulfonylchloride, 0.001 g of pmethoxyphenol, were dissolved in 14 g ofa mixed solution of dichloroethylene/methyl ethyl ketone (1:1 by volume), the solution was coated on a silicate treated aluminum plate as described in Example 5 using a No. 12 coating rod, and dried for 2 min. at 100C. The element was exposed to an LTF successive step wedge(- difference 0.15) for 60 sec. using a chemical lamp (Matsushita Co., FL-3OBA-37, 100 V, W), then treated with the same development solution as described in Example 5. A sensitivity of 8 (development step no.) was obtained. This is a very high sensitivity for a lithographic PS (PreSensitized Printing) Plate.

While the invention has now been described in detail and with reference to specific embodiments thereof, it will be-apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.

What is claimed is: 1. A photopolymerizable composition comprising (A) a monomer containing at least two terminal unsaturated groups and photopolymerizable upon irradiation of actinic rays and (B) as a photopolymerization accelerator for said photopolymerizable monomer, a compound represented by the formula:

cleus; R represents an alkyl group; and R represents an alkyl group or an aryl group.

2. The photopolymerizable composition of claim 1,

wherein the non-metallic atomic group formed by Z is a benzothiazole ring, a naphthothiazole ring, a naphthoselenazole ring, a benzoxazole ring or a naphthoxazole ring; R represents an alkyl group, a hydroxyalkyl group, an alkoxyalkyl group, a carboxyalkyl group, a sulfoalkyl group, a carboalkoxyalkyl group, an aralkyl group, a sulfoaralkyl group, a carboxyaralkyl group, or a vinylmethyl group; and R represents an alkyl group, an aryl group, a hydroxyaryl group, an alkoxyaryl group, a haloaryl group, or a thienyl group.

3. The photopolymerizable composition of claim 1, wherein said monomer is an acrylic acid ester of a polyol or a methacrylic acid ester of a polyol, an acrylamide, or a reaction product of a diol monoacrylate or monomethacrylate and a diisocyanate.

4. The photopolymerizable composition of claim 1, wherein said photopolymerization accelerator is present in an amount of 0.01 to 30 percent by weight to the weight of said unsaturated monomer.

5. The photopolymerizable composition of claim 4, wherein said photopolymerization accelerator is present in an amount of l to 10 percent by weight.

6. The photopolymerizable composition of claim 1, including a soluble polymer in said photopolymerizable composition.

7. The photopolymerizable composition of claim 6, wherein said soluble. polymer is an acrylic acid methyl methacrylate copolymer, a styrene/acrylic acid copolymer, a cellulose derivative having pendant carboxy groups, a polyvinyl alcohol derivative, a soluble polyamide or a polyurethane.

8. The photopolymerizable composition of claim 1, including at least one aromatic sulfonyl halide in said composition.

10. The photopolymerizable composition of claim 8, wherein said photopolymerizable accelerator and said aromatic sulfonyl halide are present in an amount of 0.01 to 30 percent by weight to said unsaturated monomer.

11. The photopolymerizable composition of claim of l to 10 percent by weight.